Acute severe deterioration in cystic fibrosis associated with influenza A virus infection

Respiratory Viruses and Cystic Fibrosis

The threat of respiratory virus infection to human health and well-being has been clearly highlighted by the coronavirus disease 2019 (COVID-19) pandemic. For people with cystic fibrosis (CF), the clinical significance of viral infections long predated the emergence of severe acute respiratory syndrome coronavirus 2. This article reviews the epidemiology, diagnosis, and treatment of respiratory virus infection in the context of CF as well as the current understanding of interactions between viruses and other microorganisms in the CF lung. The incidence of respiratory virus infection in CF varies by age with young children typically experiencing more frequent episodes than adolescents and adults. At all ages, respiratory viruses are very common in CF and are associated with pulmonary exacerbations. Respiratory viruses are identified at up to 69% of exacerbations, while viruses are also frequently detected during clinical stability. The full impact of COVID-19 in CF is yet to be established. Early studies found that rates of COVID-19 were lower in CF cohorts than in the general population. The reasons for this are unclear but may be related to the effects of shielding, infection control practices, maintenance CF therapies, or the inflammatory milieu in the CF lung. Observational studies have consistently identified that prior solid organ transplantation is a key risk factor for poor outcomes from COVID-19 in CF. Several key priorities for future research are highlighted. First, the impact of highly effective CFTR modulator therapy on the epidemiology and pathophysiology of viral infections in CF requires investigation. Second, the impact of respiratory viruses on the development and dynamics of the CF lung microbiota is poorly understood and viral infection may have important interactions with bacteria and fungi in the airway. Finally, bacteriophages represent a key focus of future investigation both for their role in transmission of antimicrobial resistance and as a promising treatment modality for multiresistant pathogens.

Infection control in cystic fibrosis: evolving perspectives and challenges

PURPOSE OF REVIEW

This article reviews the impact of some of the most recent changes in clinical care management in cystic fibrosis on infection prevention practice and advice for people with cystic fibrosis.

RECENT FINDINGS

People with cystic fibrosis (CF) consistently highlight infection control as one of their major concerns. Infection prevention guidance and practice has facilitated successful decreases in rates of many transmissible CF pathogens. The coronavirus disease 2019 pandemic highlighted the clinical significance of respiratory viral infections and has accelerated the implementation of remote monitoring and telemedicine consultations as standard practice in CF. The continued improvement in health of the CF population is being further augmented by the introduction of new therapies, in particular cystic fibrosis transmembrane conductance regulator modulators. Infection prevention will remain pertinent to CF care, but these recent changes in clinical practice will have ongoing implications for infection prevention guidance in CF.

SUMMARY

Recent changes in CF clinical care have implications that will lead to further evolution of infection control practice and advice.

Recommendations of the Italian society for infectious and tropical diseases (SIMIT) for adult vaccinations

Vaccination prevents 2-3 million deaths worldwide every year. Nevertheless, vaccine-preventable diseases (VPDs) still cause a considerable number of deaths especially in subjects belonging to "risk groups." These are represented by older adults, immunocompromised individuals and all subjects with underlying chronic medical conditions (cardiovascular, pulmonary, renal and liver chronic diseases, diabetes, immunodeficiency disorders). They have a weaker immune system and, if infected, are more likely to develop severe complications of their condition or of the preventable-infectious disease. This document summarizes the recommendations for vaccination of the main Global Institutional Organizations and analyses the risks of comorbidities associated with infectious disease and the benefits of vaccination for each specific group. The document provides a clear, practical and authoritative guide to adult vaccination.

Influenza in High-Risk Hosts-Lessons Learned from Animal Models

Factoring significantly into the global burden of influenza disease are high-risk populations that suffer the bulk of infections. Classically, the very young, very old, and pregnant women have been identified as high-risk populations; however, recent research has uncovered several other conditions that contribute to severe infection. By using varied animal models, researchers have identified molecular mechanisms underpinning the increased likelihood for infection due to obesity and malnourishment, as well as insight into the role sex hormones play in antiviral immunity in males, in females, and across the life span. Additionally, novel comorbidity models have helped elucidate the role of chronic infectious and genetic diseases in influenza virus pathogenesis. Animal models play a vital role in understanding the contribution of host factors to influenza severity and immunity. An in-depth understanding of these host factors represents an important step in reducing the burden of influenza among the growing number of people living with one or more chronic medical conditions.

Impact of influenza on hospitalization rates in children with a range of chronic lung diseases

BACKGROUND

Data on burden of severe influenza in children with a range of chronic lung diseases (CLDs) remain limited.

METHOD

We performed a cohort study to estimate burden of influenza-associated hospitalization in children with CLDs using population-based linked data. The cohort comprised all children in New South Wales, Australia, born between 2001 and 2010 and was divided into five groups, children with: (a) severe asthma; (b) bronchopulmonary dysplasia (BPD); (c) cystic fibrosis (CF); (d) other congenital/chronic lung conditions; and (e) children without CLDs. Incidence rates and rate ratios for influenza-associated hospitalization were calculated for 2001-2011. Average cost/episode of hospitalization was estimated using public hospital cost weights.

RESULTS

Our cohort comprised 888 157 children; 11 058 (1.2%) had one of the CLDs. The adjusted incidence/1000 child-years of influenza-associated hospitalization in children with CLDs was 3.9 (95% CI: 2.6-5.2) and 0.7 (95% CI: 0.5-0.9) for children without. The rate ratio was 5.4 in children with CLDs compared to children without. The adjusted incidence/1000 child-years (95% CI) in children with severe asthma was 1.1 (0.6-1.6), with BPD was 6.0 (3.7-8.3), with CF was 7.4 (2.6-12.1), and with other congenital/chronic lung conditions was 6.9 (4.9-8.9). The cost/episode (95% CI) of influenza-associated hospitalization was AUD 19 704 (95% CI: 11 715-27 693) for children with CLDs compared to 4557 (95% CI: 4129-4984) for children without.

DISCUSSION

This large population-based study suggests a significant healthcare burden associated with influenza in children with a range of CLDs.

[Influenza vaccination and cystic fibrosis. Impact of an incentivisation campaign about influenza vaccination for patients attending the Dunkerque cystic fibrosis treatment centre and their health care workers]

INTRODUCTION

The main aim of this study is to evaluate the effectiveness of preventive actions regarding influenza in the studied populations. The secondary objective is to analyze and understand the mechanisms which bring about a behavioural change regarding influenza vaccination.

METHODS

The interventional and prospective study was undertaken in the form of an anonymous questionnaire about influenza vaccination coverage and about the reasons for vaccinating or not vaccinating. The studied populations were patients followed for cystic fibrosis (n=67) in the Dunkerque cystic fibrosis treatment centre and their health care workers (n=117), before (April 2014) and after (April 2015) an information campaign and primary prevention actions (vaccination in the workplace with expanded time slots) in collaboration with the department of occupational medicine.

RESULTS

In 2015, the vaccination coverage rate of health care workers rose to 65.63%, that is to say 2.38 times more than in 2014 (27.55%). This difference is significant (χ²[1]=29.17, P<0.0001). However, no significant difference between 2014 and 2015 was observed among patients (children and adults) (χ²[1]=0.24, NS) whose vaccination coverage was already optimal before the study.

CONCLUSIONS

Raising awareness among health care workers about vaccination against influenza increases the coverage rate and decreases outbreaks of virus infection in the care services and among patients at risk. Three main levers were identified: the necessity of providing information on influenza vaccination to health care workers, the ease of vaccination access and the attitude towards vaccination of supervisory staff (health executives/doctors).

Viruses in cystic fibrosis patients' airways

Although bacteria have historically been considered to play a major role in cystic fibrosis (CF) airway damage, a strong impact of respiratory viral infections (RVI) is also now recognized. Emerging evidence confirms that respiratory viruses are associated with deterioration of pulmonary function and exacerbation and facilitation of bacterial colonization in CF patients. The aim of this review is to provide an overview of the current knowledge on respiratory viruses in CF airways, to discuss the resulting inflammation and RVI response, to determine how to detect the viruses, and to assess their clinical consequences, prevalence, and interactions with bacteria. The most predominant are Rhinoviruses (RVs), significantly associated with CF exacerbation. Molecular techniques, and especially multiplex PCR, help to diagnose viral infections, and the coming rise of metagenomics will extend knowledge of viral populations in the complex ecosystem of CF airways. Prophylaxis and vaccination are currently available only for Respiratory syncytial and Influenza virus (IV), but antiviral molecules are being tested to improve CF patients' care. All the points raised in this review highlight the importance of taking account of RVIs and their potential impact on the CF airway ecosystem.

Study of Greek children and youths with cystic fibrosis identifies immunisation gaps and delays

AIM

Data about immunisation rates in cystic fibrosis (CF) patients are scarce. We estimated the rates and timeliness of immunisations in CF patients aged 0.55-22 years.

METHODS

We studied 122 subjects at a hospital in Greece in 2014. A standard questionnaire was used to collect data and parents' opinions about immunisations.

RESULTS

The complete immunisation rates were 92.6% for diphtheria-tetanus-acellular pertussis-inactivated poliomyelitis-Haemophilus influenzae (DTaP-IPV-Hib), 96.7% for hepatitis A, 97.4% for hepatitis B, 97.4% for measles-mumps-rubella, 85.1% for the varicella zoster virus, 85.1% for the meningococcus C conjugate, 84.3% for the pneumococcus conjugate and 58.9% for the bacillus Calmette-Guérin vaccine. Immunisation rates in youths were 64.4% for DTaP-IPV, 26.8% for the tetravalent meningococcus conjugate vaccine and 54.1% for the human papilloma virus vaccine. In addition, 30.1% received the 23-valent pneumococcal polysaccharide vaccine and 45.6% received annual influenza vaccines. Complete, up-to-date immunisation rates fell from 61.4% at 12 months of age to 14.5% at six and 12 years. All vaccines experienced delays. Most parents believed vaccines were necessary to protect their child's health.

CONCLUSION

Our study of children with CF found immunisation gaps with no catch-up immunisations and these need to be administered at follow-up visits.

Neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is the most common, life-threatening, recessively inherited disease of Caucasian populations. It is a multisystem disorder caused by a mutation in the gene encoding the cystic fibrosis transmembrane conductance regulator protein which is important in producing sweat, digestive juices and mucus.The impaired or absent function of this protein results in the production of viscous mucus within the lungs and an environment that is susceptible to chronic airway obstruction and pulmonary colonization by a range of pathogenic bacteria. Morbidity and mortality of cystic fibrosis is related to chronic pulmonary sepsis and its complications by these bacteria.Influenza can worsen the course of the disease in cystic fibrosis by increasing the risk of pneumonia and secondary respiratory complications. Antiviral agents form an important part of influenza management and include the neuraminidase inhibitors zanamivir and oseltamivir. These inhibitors can limit the infection and prevent the spread of the virus.

OBJECTIVES

To assess the effects of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search: 02 November 2015.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing neuraminidase inhibitors with placebo or other antiviral drugs.

DATA COLLECTION AND ANALYSIS

Two review authors had planned to independently screen studies, extract data and assess risk of bias using standard Cochrane methodologies. No studies were identified for inclusion.

MAIN RESULTS

No relevant studies were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled studies or quasi-randomised controlled studies on the efficacy of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis. The absence of high level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately powered, randomised controlled clinical studies.

Lessons from a French collaborative case-control study in cystic fibrosis patients during the 2009 A/H1N1 influenza pandemy

Background

Viral infections such as influenza are thought to impact respiratory parameters and to promote infection with Pseudomonas aeruginosa in patients with cystic fibrosis (CF). However, the real morbidity of the influenza virus in CF needs to be further investigated because previous studies were only observational.

Methods

CF patients were included in a case–control study (n = 44 cases and n = 371 controls) during the 2009 pandemic A/H1N1 influenza. Cases were patients with polymerase reaction chain-confirmed influenza A/H1N1 infection. Controls did not report any influenza symptoms during the same period. Sputum colonization and lung function were monitored during 1 year after inclusion.

Results

Cases were significantly younger than controls (mean(SD) 14.9 years(11) versus 20.1 years (13.2) and significantly less frequently colonized with P. aeruginosa (34 % versus 53 %). During influenza infection, 74 % of cases had pulmonary exacerbation, 92 % had antibiotics adapted to their usual sputum colonization and 82 % were treated with oseltamivir. Two cases required lung transplantation after A/H1N1 infection (one had not received oseltamivir and the other one had been treated late). The cases received a mean number of antibiotic treatments significantly higher during the year after the influenza infection (mean(SD) 2.8 (2.4) for cases versus 1.8(2.1) for controls; p = 0.002). An age-matched comparison did not demonstrate any significant modification of bronchopulmonary bacterial colonization during the year after influenza infection nor any significant change in FEV1 at months 1, 3 and 12 after A/H1N1 infection.

Conclusions

Our results do not demonstrate any change in sputum colonization nor significant lung disease progression after pandemic A/H1N1 influenza.

Trial registration

Clinical Trials.gov registration number: NCT01499914

Treatment of resistant influenza virus infection in a hospitalized patient with cystic fibrosis with DAS181, a host-directed antiviral

We report a cystic fibrosis patient infected with influenza 2009H1N1 who had persistent viral shedding and clinical deterioration despite prolonged treatment with oseltamivir and zanamivir. The patient was diagnosed with H275Y neuraminidase inhibitor resistant influenza during treatment, thus was treated for 10 days with DAS181, an investigational host-directed inhaled sialidase fusion protein. Viral clearance occurred after 5 days of therapy and the patient became eligible for lung transplantation. Although the patient succumbed prior to receiving a transplant, this case exemplifies the potential utility of a host-directed approach against influenza which has potential to become resistant to neuraminidase inhibitors.

Safety of live-attenuated influenza vaccination in cystic fibrosis

OBJECTIVES

Given the improved efficacy of the nasal live-attenuated influenza virus vaccine (LAIV) compared with the injectable vaccine in children, we aimed to determine its safety in individuals with cystic fibrosis (CF).

METHODS

A cohort of 168 study participants, aged 2 to 18 years with CF, vaccinated with LAIV between October 1, 2012, and January 30, 2013, was followed prospectively for 56 days after initial vaccination in 3 pediatric CF clinics across the province of Quebec. Days 0 to 28 post-LAIV were considered the at-risk period for all outcomes of interest, and days 29 to 56 post-LAIV were considered the non-at-risk period. Incident respiratory deteriorations were defined as an unscheduled medical visit, hospitalization, or a new course of oral antibiotics for respiratory complaints. Using a self-controlled design, incidence rate ratios (IRR) were used to compare at-risk and non-at-risk periods.

RESULTS

Comparing at-risk to non-at-risk periods, there was no significant increase in the rate of incident respiratory deteriorations (IRR, 0.72; 95% confidence interval, 0.11-4.27) or all-cause hospitalizations (IRR, 1.16; 95% confidence interval, 0.30-4.81). A greater proportion of participants reported experiencing at least 1 minor respiratory and/or systemic adverse event after immunization during the at-risk period compared with the non-at-risk period (77% vs 54%, respectively). During the first week after LAIV, 13 of 168 (8%) children reported some wheezing, with the vast majority, 9 of 13 (69%), on the day of vaccination.

CONCLUSIONS

There was no increased risk of respiratory deterioration or all-cause hospitalization associated with LAIV in our study population. LAIV seems well tolerated in children and adolescents with CF.

Vaccines for preventing influenza in people with cystic fibrosis

BACKGROUND

Viral respiratory tract infections in people with cystic fibrosis have a deteriorating effect on their lung function and disease progression. Annual influenza vaccination is therefore commonly recommended for people with cystic fibrosis.

OBJECTIVES

To assess the effectiveness of influenza vaccination for people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises of references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also contacted the companies which market the influenza vaccines used in the trials to obtain further information about randomised controlled trials.Date of the most recent search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register: 08 July 2013.

SELECTION CRITERIA

All randomised and quasi-randomised trials (published or unpublished) comparing any influenza vaccine with a placebo or with another type of influenza vaccine.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Additional information was obtained by contacting the investigators when it was indicated.

MAIN RESULTS

Four studies enrolling a total of 179 participants with cystic fibrosis (143 (80%) were children aged 1 to 16 years) were included in this review. There was no study comparing a vaccine to a placebo or a whole virus vaccine to a subunit or split virus vaccine. Two studies compared an intranasal applied live vaccine to an intramuscular inactivated vaccine and the other two studies compared a split virus to a subunit vaccine and a virosome to a subunit vaccine (all intramuscular). The incidence of all reported adverse events was high depending on the type of influenza vaccine. The total adverse event rate ranged from 48 out of 201 participants (24%) for the intranasal live vaccine to 13 out of 30 participants (43%) for the split virus vaccine. With the limitation of a statistical low power there was no significant difference between the study vaccinations. None of the events were severe. All study influenza vaccinations generated a satisfactory serological antibody response. No study reported other clinically important benefits.

AUTHORS' CONCLUSIONS

There is currently no evidence from randomised studies that influenza vaccine given to people with cystic fibrosis is of benefit to them. There remains a need for a well-constructed clinical study, that assesses the effectiveness of influenza vaccination on important clinical outcome measures.

Neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is the most common, life-threatening, recessively inherited disease of Caucasian populations. It is a multisystem disorder caused by a mutation in the gene encoding the cystic fibrosis transmembrane conductance regulator protein which is important in producing sweat, digestive juices and mucus.The impaired or absent function of this protein results in the production of viscous mucus within the lungs and an environment that is susceptible to chronic airway obstruction and pulmonary colonization by a range of pathogenic bacteria. Morbidity and mortality of cystic fibrosis is related to chronic pulmonary sepsis and its complications by these bacteria.Influenza can worsen the course of the disease in cystic fibrosis by increasing the risk of pneumonia and secondary respiratory complications. Antiviral agents form an important part of influenza management and include the neuraminidase inhibitors zanamivir and oseltamivir. These inhibitors can limit the infection and prevent the spread of the virus.

OBJECTIVES

To assess the effects of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search: 08 July 2013.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing neuraminidase inhibitors with placebo or other antiviral drugs.

DATA COLLECTION AND ANALYSIS

Two review authors had planned to independently screen studies, extract data and assess risk of bias using standard Cochrane Collaboration methodologies. No studies were identified for inclusion.

MAIN RESULTS

No relevant studies were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled trials or quasi-randomised controlled trials on the efficacy of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis. The absence of high level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately powered, randomised controlled clinical trials.

Incidence and clinical impact of respiratory viruses in adults with cystic fibrosis

BACKGROUND

Viral respiratory infection (VRI) is a common cause of pulmonary exacerbations in children with cystic fibrosis (CF). The importance of VRI in adult CF populations is unclear.

OBJECTIVE

To determine the incidence and clinical impact of VRI among adults with CF.

METHODS

One hundred adults with CF were followed up prospectively for 12 months. Sputum, nose swabs and throat swabs were collected every 2 months and at onset of pulmonary exacerbation. PCR assays for adenovirus, influenza A&B, human metapneumovirus, parainfluenza 1-3, respiratory syncytial virus and human rhinovirus were performed on each sample. Symptom scores, spirometry and inflammatory markers were measured at each visit.

RESULTS

One or more respiratory viruses were detected in 191/626 (30.5%) visits. Human rhinovirus accounted for 72.5% of viruses. Overall incidence of VRI was 1.66 (95% CI 1.39 to 1.92) cases/patient-year. VRI was associated with increased risk of pulmonary exacerbation (OR=2.19; 95% CI 1.56 to 3.08; p<0.001) and prescription of antibiotics (OR=2.26; 95% CI 1.63 to 3.13; p<0.001). Virus-positive visits were associated with higher respiratory symptom scores and greater C-reactive protein levels. Virus-positive exacerbations had a lower acute fall in FEV1 than virus-negative exacerbations (12.7% vs 15.6%; p=0.040). The incidence of exacerbations, but not VRI, was associated with greater lung function decline over 12 months (-1.79% per pulmonary exacerbation/year; 95% CI -3.4 to -0.23; p=0.025).

CONCLUSION

VRI is common in adults with CF and is associated with substantial morbidity. Respiratory viruses are a potential therapeutic target in CF lung disease.

Influenza vaccination in children with cystic fibrosis

Cystic fibrosis (CF) is an inherited autosomal recessive disease characterized by progressive pulmonary damage and respiratory failure. It is known that bacterial infections play a critical role in the development of significant lung damage, whereas the role of respiratory viruses in CF pulmonary exacerbations and the relationship between viral infections and the progression of lung damage are uncertain. Health authorities throughout the world recommend influenza vaccination for CF patients. The aim of this review is to analyze the impact of seasonal and pandemic influenza on CF patients and data concerning influenza vaccination in order to assess the current situation and identify areas for future study. As data are limited, further well-constructed clinical studies of the effectiveness of influenza vaccination on the main clinical outcome measures of pulmonary function and nutritional status in patients with CF are required.

Influenza vaccination in children at high risk of respiratory disease

Chronic respiratory diseases (CRDs) are a heterogeneous group of diseases that can affect the pediatric population and health authorities throughout the world recommend influenza vaccination because of the significant risk of influenza-related complications. However, despite this recommendation, vaccine coverage is generally unsatisfactory. The aim of this review is to analyze the impact of influenza on children at high risk of respiratory disease, and the immunogenicity, safety and efficacy of influenza vaccination in such children. The results show that there is a significant risk of influenza-related complications in preterm neonates and infants, in whom influenza vaccines are immunogenic and safe (although their efficacy has not been specifically studied). There are conflicting data concerning the effect of influenza infection on asthma morbidity in children, and whether or not influenza vaccination helps to prevent asthma exacerbations. Recent data provide no evidence that influenza is more frequent in patients with cystic fibrosis than in healthy subjects, or that it is responsible for increased lower respiratory tract morbidity. The lack of any clear correlate of protection suggests that future studies should also consider the efficacy of the different influenza vaccines and not only evaluate them in terms of immunogenicity. Furthermore, there is a need for clinical studies to assess the effectiveness of the available vaccines in patients with other rare CRDs and other chronic underlying diseases with possibly severe respiratory involvement. It is also important to determine whether children with recurrent respiratory tract infections should be included in the list of those for whom influenza vaccination is recommended. In the meantime, given the increasing evidence of the burden of influenza on the population as a whole and the benefits associated with vaccination, annual influenza vaccinations should be recommended for all children at high risk of respiratory disease and the members of their households.

Spectrum of viral infections in patients with cystic fibrosis

This review explores the extensive influence of viral infections leading to chronic deterioration of lung function in patients with cystic fibrosis (CF). The mechanisms how viral agents affect the pathogenesis as well as the inflammatory and immune response of CF are discussed. Viral infections of the upper and lower respiratory tract due to viruses in CF patients and methods for diagnosis of respiratory viruses are described in detail. The importance of respiratory and non-respiratory viral agents for the pathogenesis, especially for the exacerbation of bacterial lower respiratory tract infections and course of CF, is stressed, especially emphasizing respiratory syncytial virus, influenza virus, rhinovirus, and human herpes viruses. Possible harmful effects of further viruses like adenovirus, bocavirus, coronavirus, metapneumovirus, parainfluenzavirus on the lung function of CF patients are discussed. The potential use of adenovirus-based vectors for somatic gene therapy is mentioned.

Determinants of refusal of A/H1N1 pandemic vaccination in a high risk population: a qualitative approach

BACKGROUND

Our study analyses the main determinants of refusal or acceptance of the 2009 A/H1N1 vaccine in patients with cystic fibrosis, a high-risk population for severe flu infection, usually very compliant for seasonal flu vaccine.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a qualitative study based on semi-structured interviews in 3 cystic fibrosis referral centres in Paris, France. The study included 42 patients with cystic fibrosis: 24 who refused the vaccine and 18 who were vaccinated. The two groups differed quite substantially in their perceptions of vaccine- and disease-related risks. Those who refused the vaccine were motivated mainly by the fears it aroused and did not explicitly consider the 2009 A/H1N1 flu a potentially severe disease. People who were vaccinated explained their choice, first and foremost, as intended to prevent the flu's potential consequences on respiratory cystic fibrosis disease. Moreover, they considered vaccination to be an indirect collective prevention tool. Patients who refused the vaccine mentioned multiple, contradictory information sources and did not appear to consider the recommendation of their local health care provider as predominant. On the contrary, those who were vaccinated stated that they had based their decision solely on the clear and unequivocal advice of their health care provider.

CONCLUSIONS/SIGNIFICANCE

These results of our survey led us to formulate three main recommendations for improving adhesion to new pandemic vaccines. (1) it appears necessary to reinforce patient education about the disease and its specific risks, but also general population information about community immunity. (2) it is essential to disseminate a clear and effective message about the safety of novel vaccines. (3) this message should be conveyed by local health care providers, who should be involved in implementing immunization.

Impact of the A (H1N1) pandemic influenza (season 2009-2010) on patients with cystic fibrosis

BACKGROUND

Influenza, like other respiratory viral infections, can cause acute deterioration of lung function in patients with cystic fibrosis (CF). Previous studies on a small number of patients reported that most people with CF infected with A (H1N1) influenza experienced a mild course of disease.

AIM

To characterise the impact of A (H1N1) infection on CF in a large number of patients from different centres and countries.

METHODS

CF centres accessing the web-site of the European Cystic Fibrosis Society (ECFS) were asked to report clinical data on patients with an ascertained diagnosis of influenza caused by the A (H1N1) virus. The study was web-based and data were collected through an electronic data sheet on the ECFS website.

RESULTS

Twenty-five centres from 10 countries caring for 4698 patients with CF reported data on 110 patients (2.3%), median age 13 years (range 1-39 years). The prevalence of infection in each centre ranged from 0% to 9.4%. Only 8.8% of the patients had been vaccinated. The main symptoms were fever and respiratory exacerbation requiring IV antibiotics in 53% of the patients; 48% of the patients were hospitalised for an average of 12.9 days (range 2-56) and 31% required oxygen treatment during the time of the infection. Most of the patients recovered and FEV(1) 1 month after the infection was similar to that before the infection. However, 6 patients were admitted to ICU, 5 with mechanical ventilation. Three patients with severe respiratory disease died.

CONCLUSIONS

A (H1N1) influenza infection caused transient but significant morbidity in most of the patients with CF. However, in a small number of patients with severe lung disease, A (H1N1) influenza was associated with respiratory deterioration, mechanical ventilation and even death.

Pharmacokinetics and diffusion into sputum of oseltamivir and oseltamivir carboxylate in adults with cystic fibrosis

Oseltamivir is a prodrug of oseltamivir carboxylate (OC), a neuraminidase inhibitor used for treatment and prevention of influenza. The pharmacokinetics of these 2 compounds were investigated after a single 75-mg oseltamivir dose in 6 patients with cystic fibrosis (CF). Means ± standard deviations of the area under the curve from time zero to infinity (AUC) were 173 ± 58 μg · h/liter for oseltamivir and 2,256 ± 394 μg · h/liter for OC. The concentrations of OC in sputum 4 to 6 h and 22 to 26 h after the intake ranged from 4.1 to 62.2 μg/liter. The AUC of OC was approximately 30% lower than and significantly different from published values for volunteers. On the basis of the present results and because the anti-A/H1N1 influenza virus efficacy of OC is related to its AUC/50% effective concentration (EC(50)) ratio, an increase in the oseltamivir unitary dose could be considered for the treatment of influenza in CF patients. This should nevertheless be confirmed by a controlled pharmacokinetic study performed on a larger number of patients.

Persistent oseltamivir-resistant pandemic influenza A/H1N1 infection in an adult with cystic fibrosis

The authors report the case of a 25-year-old patient with cystic fibrosis (CF) who developed pandemic influenza A/H1N1 during a visit to the USA in August 2010. The patient has severe CF lung disease and takes maintenance oral corticosteroids. The influenza virus was positive for the H275Y oseltamivir-resistance mutation despite the patient never having received oseltamivir. The patient has remained sputum-positive for over 4 months despite inhaled zanamivir therapy. This is the first reported case of transmission of oseltamivir-resistant H1N1 influenza to a patient with CF. The frequency of prolonged sputum carriage of pandemic influenza and transmission of oseltamivir-resistant strains are unknown on a population level. However, if our observations are replicated in other CF patients, they are potentially of considerable importance to clinical and infection-control practices in this patient group.

Neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is the most common, life-threatening, recessively inherited disease of Caucasian populations. It is a multisystem disorder caused by a mutation in the gene encoding the cystic fibrosis transmembrane conductance regulator protein which is important in producing sweat, digestive juices and mucus.The impaired or absent function of this protein results in the production of viscous mucus within the lungs and an environment that is susceptible to chronic airway obstruction and pulmonary colonization by a range of pathogenic bacteria. Morbidity and mortality of cystic fibrosis is related to chronic pulmonary sepsis and its complications by these bacteria.Influenza can worsen the course of the disease in cystic fibrosis by increasing the risk of pneumonia and secondary respiratory complications. Antiviral agents form an important part of influenza management and include the neuraminidase inhibitors zanamivir and oseltamivir. These inhibitors can limit the infection and prevent the spread of the virus.

OBJECTIVES

To assess the effects of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search: 12 August 2009.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing neuraminidase inhibitors with placebo or other antiviral drugs.

DATA COLLECTION AND ANALYSIS

Two review authors had planned to independently screen studies, extract data and assess risk of bias using standard Cochrane Collaboration methodologies. No studies were identified for inclusion.

MAIN RESULTS

No relevant studies were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled trials or quasi-randomised controlled trials on the efficacy of neuraminidase inhibitors for the treatment of influenza infection in people with cystic fibrosis. The absence of high level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately powered, randomised controlled clinical trials.

The month of July: an early experience with pandemic influenza A (H1N1) in adults with cystic fibrosis

Background

Pandemic Influenza A (H1N1) 2009 is a novel viral infection that emerged in March 2009. This is the first report addressing the clinical course of patients with cystic fibrosis (CF) and H1N1 infection.

Methods

All patients with an influenza-like illness (ILI) attending our adult centre during July 2009 were identified. Baseline respiratory function, nutritional status, approach to management and short-term clinical course were recorded.

Results

Most patients experienced a mild course and were able to be managed with antiviral agents as an outpatient. Robust infection control policies were implemented to limit transmission of H1N1 infection within our CF centre. Patients with severe lung disease, poor baseline nutritional reserve and presenting with more than 48 hours of ILI experienced a more severe course. Prompt antiviral therapy within the first 48 hours of illness may have been important in improving outcomes.

Conclusions

This observational study demonstrates that most adults with CF with H1N1 infection had mild clinical courses and recovered rapidly.

Vaccines for preventing influenza in people with cystic fibrosis

BACKGROUND

Viral respiratory tract infections in people with cystic fibrosis (CF) have a deteriorating effect on their lung function and disease progression. Annual influenza vaccination is therefore commonly recommended for people with CF.

OBJECTIVES

To assess the effectiveness of influenza vaccination for people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises of references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also contacted the companies which market the influenza vaccines used in the trials to obtain further information about randomised controlled trials.Date of the most recent search of the Cystic Fibrosis Trials Register: 05 March 2009.

SELECTION CRITERIA

All randomised and quasi-randomised trials (published or unpublished) comparing any influenza vaccine with a placebo or with another type of influenza vaccine.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Additional information was obtained by contacting the investigators when it was indicated.

MAIN RESULTS

Four studies enrolling a total of 179 participants with CF (143 (80%) were children aged 1 to 16 years) were included in this review. There was no study comparing a vaccine to a placebo or a whole virus vaccine to a subunit or split virus vaccine. Two studies compared an intranasal applied live vaccine to an intramuscular inactivated vaccine and the other two studies compared a split virus to a subunit vaccine and a virosome to a subunit vaccine (all intramuscular). The incidence of all reported adverse events was high depending on the type of influenza vaccine. The total adverse event rate ranged from 48 out of 201 participants (24%) for the intranasal live vaccine to 13 out of 30 participants (43%) for the split virus vaccine. With the limitation of a statistical low power there was no significant difference between the study vaccinations. None of the events were severe. All study influenza vaccinations generated a satisfactory serological antibody response. No study reported other clinically important benefits.

AUTHORS' CONCLUSIONS

There is currently no evidence from randomised studies that influenza vaccine given to people with CF is of benefit to them. There remains a need for a well-constructed clinical study, that assesses the effectiveness of influenza vaccination on important clinical outcome measures.

Influenza vaccination coverage in patients with cystic fibrosis followed at 12 care centers in the Greater South Region of France for the season 2005/2006

The objective of this observational study was to estimate influenza vaccination coverage for the 2005/2006 season in cystic fibrosis (CF) patients consulting at or hospitalized in 12 CF care centers. Data from 518 CF patients >6 months of age (children: 64.9%) were analyzed: 79.9% were vaccinated. The vaccination coverage was 85.6% in children, 69.4% in adults and 44.4% in transplanted patients. General practitioners vaccinated 67.9% of the patients. "Lack of time" reason was reported by 24.7% non-vaccinated patients. In France, influenza vaccination coverage in CF patients meets the National Health objective (> or =75% by 2008), but could be improved in adults and transplanted patients.

Is there a role for influenza vaccination in cystic fibrosis?

BACKGROUND

Influenza vaccination is generally recommended to patients with Cystic Fibrosis (CF). Previous studies have shown that influenza infections cause worsening lung functions, disease progression and increase propensity of bacterial infections in CF. However, the clinical evidence in the effectiveness of influenza vaccination in CF is lacking.

AIMS

This study retrospectively reviewed the influenza vaccination status in the patients with CF and compared the influenza infection rates between the vaccinated and non-vaccinated groups. Finally the factors associated with non-adherence with vaccination were determined.

METHODS

Nasal swabs were obtained from 63 patients with CF between the age of 6 months to 18 years routinely and during respiratory exacerbations between October 2003 to April 2004. Influenza A and Influenza B were detected using Nucleic Acid Sequence Based Amplification (NASBA). The influenza vaccination status of these patients was retrospectively reviewed.

RESULTS

41 patients (65%) were vaccinated against influenza. For the 22 patients (35%) who were not vaccinated, 7 of them were scared of needles leading to non-adherence. Influenza virus was detected on 5 occasions; 3 were Influenza A (60%) and 2 were Influenza B (40%). 1 virus in the vaccinated group and 4 in the non-vaccinated were detected during the study period (p-value=0.046).

CONCLUSIONS

Although the current available evidence to support routine influenza vaccination is limited in CF, this study has shown that such practice may yet play a role in preventing its subsequent acquisition.

Ten years of viral and non-bacterial serology in adults with cystic fibrosis

Viral infections are associated with pulmonary exacerbations in children with cystic fibrosis (CF), but few studies have addressed the frequency in adults. This paper investigates the frequency and impact of viral infections in adults with CF receiving intravenous antibiotics. Pre- and post-treatment spirometry, inflammatory markers and antibody titres against influenza A, influenza B, adenovirus, respiratory syncytial virus, Mycoplasma pneumoniae, Chlamydia psittaci, and Coxiella burnetti were analysed over a 10-year period. Non-bacterial infections were identified in 5.1% of 3156 courses of treatment. The annual incidence of admissions per patient associated with viral infection was 4.9%. The presence of viral infection in association with a pulmonary exacerbation did not adversely affect lung function or inflammatory markers in the short term. Adults with CF have a lower incidence of respiratory viral infections associated with pulmonary exacerbations requiring intravenous antibiotics compared to children and infants with CF.

Tracheobronchitis in the Intensive Care Unit

Tracheobronchitis can be broadly defined as inflammation of the airways between the larynx and the bronchioles. Clinically, this syndrome is recognized by an increase in the volume and purulence of the lower respiratory tract secretions and is frequently associated with signs of variable airflow obstruction. In the intensive care unit (ICU), tracheobronchitis is a relatively common problem with an incidence as high as 10.6% [1]. Although tracheobronchitis is associated with a significantly longer length of ICU stay and a prolonged need for mechanical ventilation, it has not been shown to increase mortality. These outcomes can be improved through the use of antimicrobial agents [1].

Immunisation in the current management of cystic fibrosis patients

Although no special recommendations exist, clearly patients with cystic fibrosis (CF) can benefit from immunisation. We reviewed the literature regarding vaccination in CF and other chronic diseases. CF subjects should follow national immunisation programmes without delay to obtain optimal vaccination coverage. Indeed they may escape normal programmes due to frequent hospital admissions and school absenteeism and may be more at risk to get "vaccine-controlled" diseases at any age. There is no uniform European immunisation schedule for basic infant and childhood vaccines or for vaccines against hepatitis A (HAV) and B (HBV), varicella (VZ) and booster vaccinations. HAV and HBV vaccination is appropriate in CF as recommended in general for patients with chronic liver disease (CLD). Varicella (VZ) vaccination is not recommended in all European countries. There are no recent data about possible worsening of pulmonary status following VZ in CF, but it is known to cause pulmonary damage in non-CF adults and to be potentially fatal post transplantation and during steroid treatment. Therefore it is recommended at least for seronegative adolescents and transplant candidates. Influenza vaccine is recommended annually for CF patients aged > or =6 months. Pneumococcal vaccine is generally indicated for CF patients. RSV infection might play a role in the initial Pseudomonas colonization and the decline in pulmonary function. However no RSV vaccine is available at present. There are no recommendations for palivizumab in CF as an alternative but expensive prophylaxis. Anti-bacterial vaccinations protecting directly against Pseudomonas aeruginosa colonisation are promising for the future, potential candidates are currently being assessed in phase III clinical trials. More studies are needed to complete recommendations especially for CF adults and transplant candidates.

Method for detection of respiratory viruses in the sputa of patients with cystic fibrosis

Since the role of respiratory viruses in lung exacerbations of patients with cystic fibrosis has been hampered by the difficulty of detecting viruses in viscous sputum specimens, a multiplex reverse transcriptase PCR (RT-PCR) assay combined with colorimetric amplicon detection was tested for the identification of seven common respiratory viruses in the sputa of cystic fibrosis patients. Of 52 sputa from 38 patients, 12 (23%) samples from 12 patients were positive for a respiratory virus (4 for influenza B, 3 for parainfluenza 1, 3 for influenza A and 2 for respiratory syncytial virus). These results suggest that the RT-PCR method carried out on sputum may provide a convenient means of investigating the role of virus infection in lung exacerbations of cystic fibrosis patients.

Early intervention and prevention of lung disease in cystic fibrosis: a European consensus

In patients with cystic fibrosis (CF), early intervention and prevention of lung disease is of paramount importance. Principles to achieve this aim include early diagnosis of CF, regular monitoring of the clinical status, various hygienic measures to prevent infection and cross-infection, early use of antibiotic courses in patients with recurrent or continuous bacterial colonisation and appropriate use of chest physiotherapy.

Influenza immunisation in children: good for everyone or reserve for the chosen few?

Influenza infection leads to significant morbidity in children. There is a lack of sound epidemiological data to define precisely the true burden, severity and rate of complications in otherwise normal children. Effective and safe vaccines are available with the prospect of an intranasally administered live attenuated vaccine being licensed in the near future. There are few contraindications to immunisation and, for children who will benefit from the procedure, short courses of oral corticosteroids and confirmed allergy to egg can no longer be regarded as such. The uptake of immunisation in the UK and other countries in categories of children defined and targeted by the Department of Health is currently low. A number of challenges remain. Firstly, to define more precisely which children will most benefit from immunisation and, secondly, to gather much more persuasive evidence if routine immunisation of healthy children is to be contemplated. Once these strands of evidence have been pulled together we need a clear evidence-based protocol which will reassure doctors and parents of the importance, efficacy and safety of influenza immunisation in whichever group of children have been identified as appropriate recipients.

Respiratory virus infections in cystic fibrosis

Respiratory virus infections have pronounced and long-lasting effects on patients with cystic fibrosis (CF), resulting in significant declines in FVC, FEV(1) and Shwachman score, significantly increasing both the frequency and duration of hospitalisation. Deleterious effects on patients with CF have been reported for most viruses studied but the effects of respiratory syncytial virus and influenza appear the greatest. There is circumstantial evidence that respiratory virus infections may facilitate bacterial infections, particularly Pseudomonas aeruginosa.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Influenza vaccination coverage level at a cystic fibrosis center

BACKGROUND

Influenza causes substantial morbidity and mortality, particularly in vulnerable populations. Annual vaccination is the most effective means to prevent or attenuate this illness. The vaccine is recommended for patients with cystic fibrosis (CF) older than 6 months, but the degree of adherence with this recommendation is unknown.

OBJECTIVES

To determine 1) the vaccination coverage level for the 1997-1998 influenza season in a population of CF patients, and 2) the factors associated with nonadherence with vaccination.

DESIGN

Retrospective chart review, a mailed survey, and telephone interviews.

SETTING

Intermountain CF Center. This center, accredited by the CF Foundation, delivers health care to affected individuals throughout the Intermountain West. Care of children and adults is based at Primary Children's Medical Center and the University of Utah Hospital, respectively. The adjacent hospitals are comprehensive, tertiary care medical centers on the University of Utah campus in Salt Lake City. Approximately one third of the center's patient population lives in southern Idaho. There are 2 affiliate centers in Idaho, one based in Pocatello/Idaho Falls and the other in Boise.

PATIENTS

All patients over 6 months of age on the center's roster.

RESULTS

We found documentation of influenza vaccination status in the medical records of 99 patients; 98 who received the vaccine and 1 who did not because of an allergy to egg products. Through the mailed surveys and telephone interviews, we collected data on 236 additional patients. Thus, we report data on 335 (92.5%) of 362 patients on the center's roster. A total of 256 (76.4%) of 335 patients received the influenza vaccine before the 1997-1998 flu season, including 181 (79.4%) of 228 children (<18 years of age) and 75 (70.1%) of 107 adult patients (</=18 years of age). We also analyzed the data assigning all patients to their major site of care, either the Salt Lake parent center or one of the Idaho affiliates. We found no difference in the vaccination rate when comparing parent center to affiliates: 179 (78.2%) of 229 patients at the parent center were vaccinated versus 77 (72.6%) of 106 patients at the affiliates. For the 79 patients who did not obtain the influenza vaccine, the major reasons were: "forgot," "too healthy," "too busy," "worried about the side effects," or "too sick at the time." The unvaccinated group had fewer clinic visits, fewer CF-related hospitalizations, and lived further from the care center than the vaccinated group. To further explore the association between contact with the center and vaccination status, we categorized patients into those who were evaluated in the outpatient clinic and/or hospitalized in 1997 and those who were not. We found that 80.8% of the 281 patients who actually received care at the center during 1997 were vaccinated as compared with only 59.5% of the 42 patients who did not receive care during that year. The timing of clinic visits also appears to be a critical factor. We found that 87.1% of patients who had a visit during the fourth quarter of the year had the vaccination as compared with 64.9% of patients who did not have a fourth quarter visit. A fourth quarter visit remained highly associated with vaccination in a logistic regression analysis, whereas number of clinic visits did not.

CONCLUSIONS

The vaccination coverage level in this vulnerable population is higher than other high-risk groups of comparable age. Nonetheless, there is room for improvement. Strategies aimed at increasing patient contact with the CF center, particularly during the fourth quarter of the calendar year, may result in improved vaccination rates. Additional data encompassing a cross-section of CF centers would be helpful in ensuring that influenza vaccination is receiving adequate attention in this patient population. Systematic monitoring of influenza vaccination rates at a national level should be considered as a means of encouraging compliance with this important preventive measure. cystic fibrosis, influenza, vaccination, health care delivery.

Pneumonia due to viral and atypical organisms and their sequelae

Most children presenting with pneumonia in the industrialised world will have a viral or 'atypical' organism. The clinical features of these 'atypical' pneumonias may be indistinguishable from bacterial pneumonia. New diagnostic techniques such as the polymerase chain reaction may help in diagnosis and choice of treatment, where appropriate. The pathological and clinical features of infection with each agent are discussed, together with their sequelae.

Vaccines for preventing influenza in people with cystic fibrosis

BACKGROUND

Viral respiratory tract infections in patients with cystic fibrosis have a deteriorating effect on their lung function and disease progression. Annual influenza vaccination is therefore commonly recommended for patients with cystic fibrosis.

OBJECTIVES

To assess the effectiveness of influenza vaccination for patients with cystic fibrosis.

SEARCH STRATEGY

We have used the Cochrane Cystic Fibrosis and Genetic Disorders Group specialist trials register which comprises references identified from comprehensive electronic database searches, hand searching relevant journals and abstract books of conference proceedings and communication to the drug companies marketing influenza vaccines.

SELECTION CRITERIA

All randomised and pseudorandomised trials (published or unpublished) comparing any influenza vaccine with a placebo or with another type of influenza vaccine.

DATA COLLECTION AND ANALYSIS

Both reviewers independently assessed trial quality and extracted data. Additional information were obtained by contacting the investigators when it was indicated.

MAIN RESULTS

Three trials enrolling a total of 115 patients with cystic fibrosis (76 (66%) were children aged one to 13 years) were included in this review. There was no study comparing a vaccine to a placebo or a whole virus vaccine to a sub unit or split virus vaccine. Two studies compared an intranasal applied live vaccine to an intramuscular inactivated vaccine and one study compared a split virus to a sub unit vaccine (both intramuscular). The incidence of all reported adverse events was high depending on the type of influenza vaccine. The total adverse event rate ranged from 48/201 (24%) for the intranasal live vaccine to 13/30 (43%) for the split virus vaccine. With the limitation of a statistical low power there was no significant difference between the study vaccinations. None of the events were severe. All study influenza vaccinations generated a satisfactory serological antibody response. No trial reported other clinically important benefits.

REVIEWER'S CONCLUSIONS

There is currently no evidence from randomised studies that influenza vaccine given to patients with cystic fibrosis is of benefit to them. There is a need for a well constructed clinical study, that assesses the effectiveness of influenza vaccination on important clinical outcome measures.

Potential of preventing Pseudomonas aeruginosa lung infections in cystic fibrosis patients: experimental studies in animals

In patients with cystic fibrosis (CF), respiratory tract infections caused by Staphylococcus aureus and Haemophilus influenzae are followed by Pseudomonas aeruginosa with increasing age. Chronic endobronchial lung infection with P. aeruginosa is the leading cause of morbidity and mortality. In Danish CF patients we noted that both onset of initial colonization and chronic lung infection with P. aeruginosa peaked during the winter months which is the season for respiratory virus infections. Virus may therefore pave the way for P. aeruginosa. We established a chronic P. aeruginosa lung infection in rats by embedding mucoid bacteria in seaweed alginate and installing the beads intratracheally into the lower part of the left lung. Although the rats did not suffer from CF, the antibody responses and the pathologic changes of the lungs mimicked the findings in CF patients. By using this model in normal and athymic rats we showed that the T-cell response during the "natural" course of the infection played no major role. In a model of acute P. aeruginosa pneumonia we found that the macroscopic inflammatory response of the lungs was immense and that the natural capacity to clear P. aeruginosa was very efficient and could not be improved by immunization, although high serum levels of IgM, IgG and IgA antibodies to P. aeruginosa alginate, LPS, exotoxin A and sonicate were induced. We developed a method for collecting and measuring IgA in saliva and noted that mucosal IgA antibodies were induced by vaccination; they did not significantly prevent inflammation, however. In the chronic rat model we succeeded to improve the survival significantly and to change the inflammatory response subsequent to vaccination from an acute type inflammation dominated by polymorphonuclear leukocytes (PMNs) as in CF patients to a chronic type inflammation dominated by mononuclear leukocytes. Furthermore, we found that rats immunized with an alginate containing vaccine had a significantly earlier cellular shift to a chronic type inflammation as well as a significant reduction in the severity of the macroscopic inflammation compared to two other vaccine groups and to nonimmunized controls. Similar results were obtained in rats treated with the TH1 cytokine, interferon-gamma (IFN-gamma). Several authors have shown that the lung tissue damage during chronic infection in CF patients is caused by a type III hypersensitivity reaction leading to release of elastase by PMNs surrounding the bacterial microcolonies. The cellular shift we have induced by vaccination and by IFN-gamma treatment therefore offers a possible new strategy for improving the clinical course in chronically infected CF patients.